EDL600-FM
1 / 6
Instruction manual
Rev. 1.2 - 08/03/07
1. Introduction
The
EDL600-FM
is a
dummy load
produced by RVR Elettronica SpA to be used
with FM transmitter with nominal power up to 600 W.
Dummy loads are mainly used as laboratory test devices and are often included in
redundant (1+1 or N+1) transmission systems, in which the output of the spare
transmitter is normally connected to the dummy load for test pourpouses.
The
EDL600-FM
is particularily suited for the use in compact transmission systems,
thanks to its small form-factor. The quadratic construction enables a simple installation.
2. Working Principle
Simply speaking, the
EDL600-FM
is just a 50
Ω
resistive load, optimized to work in
the audio FM band.
The applied power is dissipated by four 50
Ω
power resistors connected in a series/
parallel configuration (see the enclosed schematic), able to compensate the parasitic
capacitance of the resistors, to obtain a return loss better than 26 dB on the whole
87.5 - 108 MHz band.
The resistors are fixed on a metal heatsink, and three fans generate the air flow to let
the heat pass to the environment.
The fans are activated by a thermal bimetallic switch, that is normally opened and will
close as soon as the heatsinks temperature surpasses 55 °C.
!
WARNING:
Always connect the power source (the transmitter) using the interlock
connectors, to avoid the possibility of an excessive temperature rise that could
damage the dummy load and even the transmitter itself!
3. External Description
The following drawing shows the
dummy load
.
!
WARNING:
dont cover the airflow grid, to ensure proper functioning of the device.
